This invention relates to apparatus for filtering metallurgical slag. More particularly, this invention relates to a new and improved filtering drum used in conjunction with a metallurgical slag filtering apparatus which uniformly charges a belt used for conveying granulated slag material therefrom. The general type of filtering apparatus to which the invention is directed was disclosed in my earlier U.S. Pat. No. 4,204,855, of which all of the disclosure is incorporated herein by reference. This application presents an improved drum construction for the filtering apparatus of U.S. Pat. No. 4,204,855. Other improved features are disclosed in my U.S. application Ser. Nos. 578,817 and 578,818, now U.S. Pat. No. 4,477,349 and U.S. Pat. No. 4,493,767, respectively, all of the contents of which are incorporated herein by reference thereto.
The filtration apparatus of the type herein above discussed comprise a substantially horizontal rotary drum having filtering screens or foraminous walls along the outside surface thereof and being provided with internal vanes along the inside surface thereof for conveying metallurgical granulated slag material upwardly. Thereafter, the filtered slag falls freely onto a conveyer belt passing longitudinally through the drum. A filtering apparatus of this type will also include a feed channel through which the pulp, i.e., granulated slag and water, is fed into the drum.
In a filtration apparatus of this type, the metallurgical slag is discharged from each vane at a certain height above the conveyer belt. As a result, after a vane has discharged its contents, i.e., filtered slag, a particular time period will lapse before a subsequent vane reaches the discharge level or discharge height of the rotary drum. Consequently, piles of granulated slag will form along the length of the conveyer belt which is continually removing the slag from the rotary drum. The conveyer belt therefore, is subjected to uneven stresses and to greater wear at certain portions thereof, than if the belt were to be charged in a uniform manner.
A further problem of this uneven or nonuniform belt charging process is that the conveyer belt may deviate from its desired path as a result of the uneven distribution and therefore suffer even further damage.
A third problem with the present method of charging the conveyer belt is that the belt must be manufactured larger (i.e., wider) than is otherwise necessary. In other words, the conveyer belt must be manufactured to oversized dimensions, thereby incurring greater costs.
In view of the above discussion, it would be advantageous to alter the filtration apparatus as disclosed in my earlier U.S. Pat. No. 4,204,855 so that the conveyer belt will be subjected to uniform loading both along the length and width thereof.